Parents fed up with the soundtrack of “Frozen,” which seems to be stuck on repeat in their children’s brains, might also not want to hear this advice from a music professor at Northwestern University, who regularly deals with unrelenting melodies.

“Leave it there, and enjoy it,” said Ryan Nelson, music director in residence for Northwestern’s School of Communication. “With everything, popularity always wanes and something always replaces it.”

The tip might be too little, too late, however, for “Frozen”-fatigued parents who have taken to social media and parenting blogs to rant about the pervasiveness of the music from Disney’s highest-grossing animated movie.

“For weeks, we’ve had to look at the girls and say, ‘Girls, we need to perform, not sing the song,’ ” said Kristen Ramirez, owner of Baby Take a Bow dance studios in Roscoe Village and Winnetka, Ill., where she added a fourth “Frozen” summer camp over the weekend to accommodate the demand. “The music does take over.”

The staying power of songs such as “Let it Go,” performed by the character named Elsa in the movie, can be attributed to a quality that musicians call the “hook,” said Nelson, who oversees music theater productions at the university.

“It’s a part of a song that keeps coming back that really gets you,” he said. “It’s not just the melody, or the tune. It’s also the text and the lyrics.”

Characters from "Frozen."

Katherine McHenry, owner of Building Blocks toy stores in Lakeview and Wicker Park, Ill., said the movie’s popularity is still so strong that she had no hesitations about ordering $10,000 in “Frozen” merchandise, for which she’s allowing customers to pre-order. Minutes after sending word of the incoming goods through e-mail, McHenry started receiving phone calls and Internet orders, she said.

“I have a whole community of moms in my personal life, and also my customers, who are like, ‘We’ve watched “Frozen” four times today,’ ” she said.

Nelson said the best way to rid a mind of unwelcome music is to replace it with other catchy music. For the parents, at least, he suggests the soundtracks to musicals “Avenue Q” and “Book of Mormon,” which includes songs written by “Frozen” songwriter Robert Lopez. Kids can turn to more age-appropriate works — pop music is famous for hooks, he added.

Rochelle Adkinson, a Chicago mother whose 2-year-old daughter is a “Frozen” fanatic, has tried that but without much success.

“Sometimes I do have to consciously turn on other music so I think of something else,” Adkinson said. “And when that happens, my daughter looks at me and says, ‘Where’s Elsa?’ ”

Minneapolis performing artist Patrick Scully brings the Mississippi River Boat Ballet to the festival. No art form requires more precision than ballet, so it's anyone's guess how Scully plans to keep nearly 50 boats; sailboats, kayaks, rowing shells, even a couple of bicycle-powered pontoons in balance, here are highlights from the rehearsal.